A new analysis is challenging a report that suggests regular marijuana smoking during the teen years can lead to a long-term drop in IQ. The analysis says the statistical analysis behind that conclusion is flawed.
The original study, reported last August, included more than 1,000 people who'd been born in the town of Dunedin, New Zealand. Their IQ was tested at ages 13 and 38, and they were asked about marijuana use periodically between those ages.
Researchers at Duke University and elsewhere found that participants who'd reported becoming dependent on pot by age 18 showed a drop in IQ score between ages 13 and 38. The findings suggest pot is harmful to the adolescent brain, the researchers said.